Fan wheel

ABSTRACT

A fan wheel comprises a hub and a plurality of blades extending radially outwardly from the hub. A ring is arranged in coaxial relationship with the hub and radially between the hub and the outside periphery of the fan wheel. The ring has a plurality of defined fixing positions distributed over the periphery thereof for mounting at least one balancing weight.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the priority of German Utility model applicationSerial No 20 2005 006 043.7 filed Apr. 14, 2005, the subject-matter ofwhich is incorporated herein by reference.

FIELD OF THE INVENTION

The invention concerns a fan wheel, for example for cooling an electricmotor and parts thereof and dissipating waste heat produced thereby.

BACKGROUND OF THE INVENTION

A typical form of fan wheel which can be frequently used for example forcooling an electric motor and electronic components thereof anddissipating waste heat therefrom may comprise a hub with a plurality ofblades extending radially therefrom. A ring is arranged coaxially withrespect to the hub and radially between the hub and the outer peripheryof the fan wheel. Such a fan wheel can be found for example in EP 0 761979 A1. In that arrangement the ring disposed coaxially with respect tothe hub and arranged radially between the hub and the outer periphery ofthe fan wheel contributes to stabilising the fan wheel and stiffeningthe blades which are spaced from each other in the peripheral directionof the fan wheel. In addition to that ring, the fan wheel furtherincludes a second ring which extends along the outer periphery of thefan wheel. Now, while it may be desirable to balance a fan wheel inorder to extend the service life thereof and in order to reduceoperational noises generated thereby, that publication does not make anyreference to being able to mount a balancing weight to the fan wheel.

Reference may also be made to DE 199 57 030 A1 disclosing a rotary bodywith a ring disposed at the outer periphery thereof. That publicationteaches fixing balancing weights which are in the form of clip-onweights to curved fixing locations distributed over the periphery ofthat outer peripheral ring.

DE 1 960 505 discloses a device for balancing bladed wheels of air fans,insofar as balancing weights which are displaceable in the peripheraldirection can be provided on the blades.

Furthermore in general terms there are fan wheels with a peripheral ringprovided at the outer periphery of the wheel, in which balancing weightsin the form of clips can be mounted to the peripheral ring which is asmooth ring, for balancing purposes. A disadvantage in that case is thatthe clip-on weights can move in position, upon acceleration of the fanwheel.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a fan wheel which isstable and which can be balanced with a good secure balancing result.

A further object of the present invention is to provide a fan wheelwhich while being of a simple rational structure affords reliablebalancing operations.

Yet another object of the present invention is to provide a fan wheelwhich can be balanced in such a way that the balanced condition onceattained can be reliably maintained over a period of operation of thefan wheel.

In accordance with the present invention the foregoing and other objectsare attained by a fan wheel comprising a hub and a plurality of bladesextending radially outwardly from the hub. A ring is arranged in coaxialrelationship with the hub, radially between the hub and the outerperiphery of the fan wheel. The ring has a plurality of defined fixingpositions distributed over the periphery thereof for mounting thereto atleast one balancing weight.

As will be seen from the description hereinafter of a preferredembodiment of the fan wheel according to the invention, the underlyingnotion of the invention is to provide means for definedly fixing atleast one balancing weight in different selected positions to astabilisation or stiffening ring which is spaced radially both from theoutside diameter of the fan wheel and also from the hub thereof. Theprovision of those defined fixing positions prevents slippage of thebalancing weights in a peripheral direction, in particular upon a changein the speed of rotation of the fan wheel as upon acceleration thereof.The fact that the fixing positions are provided on the ring means thatthey can be distributed over the entire periphery of the ring and thusthe fan wheel, thereby permitting one or more balancing weights to befitted to the fan wheel in a finely stepped relationship. The fact thatthe fixing positions are provided on the stabilisation ring means that astabilisation function and a balancing function are achieved using justone common component part in the form of the ring.

Good balancing results can be achieved by arranging the fixing positionson the ring which is disposed at a radial spacing from the outerperiphery of the fan wheel. The results which can be attained can beeven more accurate than when one or more balancing weights is or arearranged at the outer periphery of the fan wheel. A further advantage ofthe fan wheel according to the invention is that the negative effects ofweight tolerances in respect of the balancing weights on the balancingresult are less significant than if the balancing weights were to befixed to the outside diameter of the fan wheel.

The fact that the fixing positions are not provided on the blades of thefan wheel and the fact that the stabilisation ring on which the fixingpositions are provided is disposed at a spacing from the outer peripheryof the fan wheel can considerably reduce the risk of deformation of ordamage to the blades when fitting a balancing weight.

In accordance with a preferred feature of the invention the definedfixing positions can be formed by a profiling of the ring. If forexample the fan wheel is produced from plastic material in the form ofan injection molding, the profile can be formed on the ring directly inproduction of the fan wheel.

In another preferred feature the profiling of the ring, at least inperipheral portions thereof, can be in the form of a sawtooth profiling.In that case the angles of all flanks of the sawtooth profiling withrespect to the ring should be of equal magnitude. With that arrangement,for example a balancing weight in the form of a clip weight can beclamped between the sawtooth configurations. The inclined flanks of theprofiling mean that the clip cannot be displaced in the peripheraldirection. A further fixing option can provide that the balancingweights are of a complementary shape in relation to the profiling inorder thereby to achieve an improved positively locking connectionbetween the profiling of the ring and the respective balancing weight.

In a preferred feature the profiling is on the radially outward side ofthe ring. The large periphery at the outside of the ring means that aplurality of defined fixing positions can thus be provided on the ring.It will be appreciated that it is also possible additionally oralternatively to provide a profiling at the side of the ring which facestowards the hub and/or at the side faces of the ring which thus face inthe axial direction of the fan wheel.

In a further preferred feature of the invention the fixing positions areformed by fixing bores which are suitably distributed over the peripheryof the ring. When the balancing weights are of a suitable configurationthey can be introduced into and then fixed in the bores. That can thusprevent subsequent displacement of the one or more balancing weights inrelation to the ring.

In another preferred feature the fixing positions can be formed byreceiving pockets which are distributed over the periphery of the ring,to receive the balancing weights.

If, in accordance with a further preferred feature of the invention, thering is of a closed configuration in the peripheral direction, it ispossible to provide a very large number of fixing positions forbalancing weights on the closed ring.

In accordance with a further preferred feature, and on the basis oftests showing that a particularly good compromise can be achievedbetween optimum stabilisation and stiffening of the fan wheel andoptimum balancing results, the diameter of the ring can correspond toapproximately half the fan wheel diameter.

A preferred feature of the invention can provide that the blades extendcontinuously from the hub to the outside diameter of the fan wheel,thereby providing a good delivery output. Depending on the respectivesituation of use however it is also possible for the blades to besubdivided into two groups of blades, more specifically a first group ofblades which extend radially between the hub and the ring and a secondgroup which extends radially between the ring and the outer periphery ofthe fan wheel. In that case the blades of different groups can bearranged in mutually displaced relationship in the peripheral direction.

In many situations of use it is advantageous if the blades are mounteddirectly to the shaft of an electric motor, in which case therefore thehub of the fan wheel is formed by the actual motor shaft. Thatconfiguration can provide that the fan wheel can be produced in aparticularly simple fashion integrally with the shaft, therebyeliminating the need to provide a hub in the true sense as a separatecomponent part of the fan wheel.

In a further preferred feature it can be provided that the balancingweight is adapted to be fixed releasably to the ring, and is thus forexample in the form of a clip which can be bent into position to hold iton the ring, in order in that way to ascertain the respective fixingposition at which the best balancing effect is achieved with arespective balancing weight.

In order to achieve a good positively locking connection between theprofiling of the ring and the balancing weight, the balancing weight maybe of a complementary shape in relation to a peripheral portion of theprofiling of the ring.

In yet another preferred feature of the invention, in addition to thering disposed radially between the hub and the outer periphery of thefan wheel, the fan wheel may have a second ring which is arranged incoaxial relationship with the first-mentioned ring, for stabilisationand stiffness reasons. In an ideal situation that secorid ring can bearranged at the outside periphery of the fan wheel.

Further objects, features and advantages of the invention will beapparent from the description hereinafter of a preferred embodiment ofthe invention.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a perspective view of a fan wheel according to theinvention, and

FIG. 2 shows an enlarged detail from FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring firstly to FIG. 1 shown therein is a fan wheel which isidentified generally by reference numeral 1 and which may comprise forexample plastic material. The fan wheel 1 can be used for example forcooling an electric motor and electronic components thereof. For thatpurpose the fan wheel 1 has a hub 2, in the center of which there isprovided an axially extending fitting opening 3, by means of which thefan wheel 1 can be fitted on to the shaft of an electric motor andsecured relative to the shaft to prevent rotation with respect thereto.

The fan wheel 1 has a plurality of blades 4, in this embodiment fiveblades, which are distributed uniformly over the periphery of the fanwheel 1 and which extend substantially radially outwardly from the hub2. It will be noted that all the blades 4 are identical and are curvedin the peripheral direction in their radially outward extent and are setat an angle relative to the axial center line 5 of the fan wheel 1.

To stabilise and stiffen the blades 4 the fan wheel 1 has a ring 7 whichis formed integrally with the blades 4. The ring 7 illustrated here isof a closed configuration. The shallow circular ring 7 extends in theperipheral direction entirely around the hub 2 and is arranged incoaxial relationship with the hub 2 and radially between the hub 2 andthe outer periphery as indicated at 6 of the fan wheel 1. The ring 7 canwiden to approximately the width of the blades 4 immediately adjacent tothe blades 4, thereby enhancing the stability and resistance to fractureof the fan wheel 1. In the illustrated embodiment the diameter of thering 7 approximately corresponds to half the diameter of the fan wheel 1but it may also be larger or smaller, inter alia in dependence on thediameter of the fan wheel.

At its outward side 8 the ring 7 is provided with a profiling 9illustrated in the form of a sawtooth profiling, with teeth 10 and toothgaps 11 which alternate in the peripheral direction around the ring 7.The tooth gaps 11 provide defined fixing positions 12 for mounting oneor more balancing weights (not shown) for balancing the fan wheel 1. Thebalancing weights used can be for example in the form of metal clipswhich are laterally inserted into one or more tooth gaps 11 as requiredand which bear against the inside 13 and the outside 8 of the ring 7 andthereby bear clampingly thereagainst. The provision of the definedfixing positions avoids displacement of the one or more balancingweights in the peripheral direction of the ring 7.

The profiling 9 is of such a configuration that the teeth 10 formisosceles triangles. It is particularly advantageous if the balancingweights are of a complementary shape to the profiling 9, at least inportions thereof, to provide a positively locking connection to the ring7. In the present case therefore each balancing weight can have at leastone tooth corresponding to a tooth 10 of the profiling 9 or a tooth gapcorresponding to a tooth gap 11 of the profiling 9.

It will be seen that in the illustrated embodiment the profiling 9 isprovided exclusively at peripheral portions 14 of the ring 7, whichextend between the blades 4.

The blades 4 of the fan wheel 1 extend continuously from the hub 2 tothe outside diameter 6 of the fan wheel 1. A second peripherally closedring 15 extends along the outer periphery of the fan wheel 1 and thusadditionally enhances the stability and stiffness of the fan wheel 1 andalso closes it off radially outwardly.

Reference will now be made to FIG. 2 showing a portion of the fan wheel1 of FIG. 1 on an enlarged scale. FIG. 2 clearly shows the sawtoothprofiling 9 on the ring 7 with the peripherally alternate teeth 10 andtooth gaps 11. The depth of the tooth gaps 11 approximately correspondsto a quarter of the thickness of the ring 7.

It will be appreciated that the above-described embodiment has been setforth solely by way of example and illustration of the principles of theinvention and that various modifications and alterations may be madetherein without thereby departing from the spirit and scope of theinvention.

1. A fan wheel comprising: a hub, a plurality of blades extending atleast substantially radially outwardly from the hub, a ring arranged incoaxial relationship with the hub and radially between the hub and theoutside diameter of the fan wheel, and on the ring a plurality ofdefined fixing positions distributed over the periphery thereof formounting at least one balancing weight.
 2. A fan wheel as set forth inclaim 1 wherein the fixing positions are formed by a profiling of thering.
 3. A fan wheel as set forth in claim 2 wherein the blades arespaced in the peripheral direction and wherein the profiling is providedexclusively between the blades.
 4. A fan wheel as set forth in claim 2wherein the profiling is in the form of sawtooth profiling at least inperipheral portions of the ring.
 5. A fan wheel as set forth in claim 2wherein the profiling is on the radial outside of the ring.
 6. A fanwheel as set forth in claim 1 wherein the fixing positions are formed byfixing bores distributed over the periphery of the ring.
 7. A fan wheelas set forth in claim 1 wherein the fixing positions are formed byreceiving pockets distributed over the periphery of the ring.
 8. A fanwheel as set forth in claim 1 wherein the ring is closed in theperipheral direction.
 9. A fan wheel as set forth in claim 1 wherein thering is of a diameter which corresponds to half the fan wheel diameter.10. A fan wheel as set forth in claim 1 wherein the blades extendcontinuously from the hub to the outside diameter of the fan wheel. 11.A fan wheel as set forth in claim 1 wherein the hub is in the form of ashaft.
 12. A fan wheel as set forth in claim 11 wherein said shaft isthe shaft of a motor.
 13. A fan wheel as set forth in claim 1 wherein atleast one balancing weight is fixed to the ring.
 14. A fan wheel as setforth in claim 13 wherein said balancing weight is releasably fixed tothe ring.
 15. A fan wheel as set forth in claim 13 wherein the balancingweight is in the form of a clip.
 16. A fan wheel as set forth in claim13 wherein the balancing weight is of complementary form to a peripheralportion of the profiling.
 17. A fan wheel as set forth in claim 1including in addition to said ring a second ring arranged in coaxialrelationship with the ring.
 18. A fan wheel as set forth in claim 17wherein the second ring is a closed ring at the outside periphery of thefan wheel.